Do you think there are aliens?

[Tellos Athenaios]

Oh, c'mon; you know what I meant. All we need to do is to initiate a project, and we can. We have/know the technology required. The same thing could have happened to alien civilizations - they visited a few alien solar system, and thought they were awesome since they could; but eventually they got bored and didn't like the costs that came with it.

Yes. Which says exactly what about space travel by aliens? That it may not happen even if it is possible?

There are also the ideas of hibernation, multi-generation space ships etc. We don't have to rely on too exotic theories for interstellar space travel to be possible.

Which is no less exotic, I'm sure. Seriously: hibernation is not an option if you want to survive your travels: one needs to eat in order to hibernate; and in order to eat one needs to wake up. So at best you merely prolong the eat-sleep cycle, which incidentally makes hibernation only practical for small-ish aliens because you cannot tend any crops or similar whilst hibernating.

EDIT: There are various other interesting Health & Safety issues regarding to hibernation & space travel, too. Chief among which is that you no longer have the environmental sanity-checks of seasons, gravity, etc. etc. to trigger interrupts in your hibernation, and keep your organs healthy.